Laboratory cabinets for use for example as incubators, heating cabinets, controlled climate cabinets, etc., are often provided with removable shelves, which rest on horizontal guides on the inner side walls of the laboratory cabinet, in the inner working space of the laboratory cabinet. The shelf may be of a grille or lattice type.
The shelf base of such a shelf may consist of a network of cross bars and longitudinal bars, which at the lateral edges extending in the direction of insertion form side bars which bear on the guides. It is also known to form such shelves as perforated trays, the shelf base of which is formed by a perforated metal sheet the edges of which are bent upwards. In the case of such shelves, the side edges extending in the direction of insertion, by means of which the shelf bears on the horizontal guides, have only a small height determined by the diameter of the side bars or by the height of the bent-up edges of the perforated trays.
The horizontal guides on the inner side walls of the laboratory cabinet may be formed by profile rails which are welded onto the inner surface of the inner side wall. The vertical distance between these profile rails can to a large extent be chosen at will. In particular, two profile rails can be located with such a small vertical separation that they enclose the side edges of an insertable lattice shelf pushed in between them with only a little play. In this manner, the insertable lattice shelf is guided without being able to tip over in the direction of insertion or in the transverse direction.
The manufacture and the material costs of profile rails fixed on the inner side walls are expensive. The profile rails also hinder cleaning of the internal space of the laboratory cabinet, which is of the greatest importance in many applications. Finally, the profile rails may also adversely affect air circulation in the internal space of the laboratory cabinet.
It is also known to form the horizontal guides from beadings pressed out in the inner side walls. These beadings can be produced economically and in addition they strengthen the inner side walls. Furthermore, no edges which can hinder cleaning and adversely effect the air circulation are formed on the inner side walls by the beadings. However, the disadvantage of the beadings is that, for material and cost determined reasons, there must be a relatively large vertical distance between them. Therefore the beadings cannot guide the side edges of a conventional shelf from above and so tipping of the shelf both in the direction of insertion and also at right angles to this direction is possible.